Environmental interventions that address the high availability of unhealthy snacks in the environment are needed to prevent a large projected increase in the incidence of obesity and cardio-metabolic disease in the U.S. Prior studies from our group and others suggests that the human preference for immediate gratification from food drives dietary overconsumption, but this knowledge has not yet translated to more effective dietary intervention strategies. This project tests whether a novel snack vending machine system that uses brief time delays to reduce the immediacy of reward from unhealthy snacks will improve the healthfulness of snack choices. The project includes two studies. First, a laboratory study will be conducted to identify the optimum time delays to apply to unhealthy snacks. One-hundred sixty-eight individuals will purchase snacks classified as healthy or unhealthy at varying delay intervals. Specific Aim 1 is to select the delay interval that produces the largest improvement in purchasing rates for healthy snacks without harming overall vending sales, a key aspect of intervention feasibility in the real world. The second study uses an experimental design to compare brief time delays, two forms of 25% differential pricing, and time delays combined with both forms of 25% differential pricing on their ability to increase purchasing of healthy snacks. The test machine will be placed in an existing, high-volume vending location, and each of these five experimental conditions will run for four weeks. Additionally, baseline purchasing under no intervention will be monitored for four weeks before and four weeks after the five experimental conditions. Specific Aim 2a compares the effects of these five interventions on the proportion of total vending sales from healthy snacks. Specific Aim 2b evaluates whether these intervention effects translate into clinically meaningful improvements in calorie and nutrient purchasing. Specific Aim 3a tests whether time delays or differential pricing harm overall vending machine sales in the test machine, and Specific Aim 3b evaluates whether snack machine sales are displaced to nearby vending machines during any of the experimental conditions. This study not only tests a compelling theory about the effects of time delays and immediate reward on food choice, but evaluates the efficacy and feasibility of a novel intervention to improve the healthfulness of snack choices in worksites, schools, and other settings.